CrowdScience - Where did Earth’s water come from?

Here's a conundrum that has captivated scientists: when Earth formed 4.5 billion years ago, our planet was essentially a ball of molten rock. Any water that might have been present during the planet's formation would surely have boiled away immediately. Yet today, water covers about 70% of Earth's surface.

So where did all this water come from? And more intriguingly, when did it arrive? Listener Bill in the USA wants to know, and Presenter Caroline Steel is after answers.

Assistant Professor Muhammad Abdul Latif is an early earth physicist at United Arab Emirates University. He explains how his modelling has helped us to understand when water first appeared in our universe.

The early earth was not a water-friendly place - a hellscape of molten rock, volcanic eruptions and constant bombardments from comets and asteroids, with high levels of solar radiation. These conditions would have evaporated the water. And according to Professor Richard Greenwood at Open University, our earth’s molten iron core would have been a ball of rust if there had been water in the proto-earth mix.

So if the water hasn’t always been here, where did it come from?

At the Natural History Museum in London, Professor Sara Russell has been comparing the isotopic "fingerprint" of Earth's water with water found in the asteroid Bennu, captured and brought back by the recent Osiris Rex NASA mission. It’s a good match for earth’s water, but could it really be the answer to our question?

Presenter: Caroline Steel Producer: Marnie Chesterton Editor: Ben Motley

(Image: Man overlooking the sea from cliff top. Credit: Gary Yeowell via Getty Images)

Unexpected Elements - Sharks, albatrosses, the Jaws theme and fishing

Shark Awareness Day on 14th July sends us on a deep dive into marine biology.

First, we learn how shark-inspired materials could help make aeroplane flights more efficient.

Next, we hear about the fish that don’t flee from sharks... instead, they seek them out to help them hunt.

Bob Duke, Meyerson Professor of Music and Human Learning at the University of Texas, Austin, joins us in the studio to reveal how and why the iconic Jaws music taps into our psychology to leave us trembling.

We also hear about a couple of tiny islands in the Southern Ocean, on which an unexpected predator is wreaking havoc.

Plus, why a tiny fish is being ground up and fed to other fish.

All that, plus many more Unexpected Elements. Presenter: Marnie Chesterton, with Leonie Joubert and Christine Yohannes Producer: Alice Lipscombe-Southwell, Imaan Moin, Minnie Harrop and Margaret Sessa Hawkins

Short Wave - Meet the Third Ever (!!) Interstellar Comet

A rare visitor from another star system has been spotted: the interstellar comet 3I/ATLAS! It was detected July 1 by the NASA-funded Asteroid Terrestrial-impact Last Alert System, or ATLAS. Most known comets orbit the Sun and are bound by the gravity of the solar system ... but this object came from far beyond the pull of our Sun, traveling 137,000 miles per hour from another star. Now, scientists are racing to get a good image of it, in the hopes it can answer big questions like: What is the universe like where this comet is from? Is the solar system we live in unique?

Want us to cover more space news? Tell us by emailing shortwave@npr.org! We'd love to know what you want to hear from us.

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Science In Action - Tracking ocean circulation systems

The European Space Agency plans to use satellite gravity data to track weakening ocean circulation systems. Rory Bingham of the University of Bristol explains how these satellites can ‘weigh’ the Earth’s water and might help resolve whether we’re approaching the climate tipping point of a shutdown of ocean circulation in the Atlantic Ocean, something we've been following for a while.

Scientists have been able to retrieve ancient proteins from fossilized tooth enamel in the Canadian High Arctic. Ryan Sinclair Paterson from the University of Copenhagen tells us how he can fill in the blanks of the molecular tree of life with these proteins from over 20 million years ago.

A few weeks ago, we discussed evidence of an impact of a massive crater in northwestern Australia from over 3 billion years ago. However, recent independent evidence from another team of geologists indicate that the size and age of this crater’s impact may not be what some had previously thought. Alec Brenner of Yale University talks us through his analysis of the geologic evidence.

Finally, we rediscover a forgotten pioneer of fusion science. Mark Cavendish discusses the research done by then-graduate student Arthur Ruhlig that helped develop the hydrogen bomb and thermonuclear physics.

Presenter: Roland Pease Producers: Imaan Moin with Alex Mansfield Production Coordinator: Jana Bennett-Holesworth

(Image: Map of North Atlantic Ocean currents, with Gulf Stream and other currents. Credit: PeterHermesFurian Via Getty Images.)

Short Wave - Evolution Went On Trial 100 Years Ago. Where Are We Now?

This week marks the 100th anniversary of the Scopes "Monkey Trial" — where a teacher was charged with the crime of teaching Darwin's theory of evolution by natural selection. At the time, it was illegal in Tennessee to "teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals." The trial, which was orchestrated to be a media spectacle, foreshadowed the cultural divisions that continue today and led to a backlash against proponents of evolution.

Read more of science correspondent Nell Greenfieldboyce's reporting on the story.

Want us to cover more science history? Less? Either way, tell us by emailing shortwave@npr.org! We'd love to know what you're hearing — and want to hear from us!

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Short Wave - Itchy? Air Pollution May Be Making It Worse

Short Wave producer Hannah Chinn has adult-onset eczema. They're not the only one. Up to ten percent of people in the United States have it, according to the National Eczema Association — and its prevalence is increasing. Despite its ubiquity, a lot about this skin condition remains a mystery.
So today, Hannah's getting answers. In this encore episode, they sat down with Raj Fadadu, a dermatologist at the University of California, San Diego, to ask: What is eczema? What triggers it in the first place? And might climate change make it worse sometimes?

If you liked this episode, check out our episode on the science of itchiness. Also, follow us! That way you never miss another episode.

Interested in hearing more about climate change and human health? Email us at shortwave@npr.orgwe'd love to hear your feedback!

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Short Wave - Sea Camp: Why Are Ocean Currents Shifting?

A warming climate doesn't just affect dry land — it affects the ocean, too. For years, Earth's ocean has acted as a heat sink for climate change: A large part of the heat generated by human use of fossil fuels is being absorbed by the ocean. And while the deep sea is largely unaffected by this heat absorption, oceanographers have discovered that the upper ocean currents are accelerating. That acceleration has the potential for huge knock-on effects, including sea level rise, changing fish migration cycles, shifting storm patterns, and more.

This is the first episode of Sea Camp, Short Wave's summer series exploring the intriguing and otherworldly depths of the ocean. Follow us every Monday through August as we travel from the sunlit zone to the sea floor.

Interested in more stories about the ocean? Email us your question at shortwave@npr.org.

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PBS News Hour - Science - Study warns 1.5-degree warming limit can’t prevent dangers of melting glaciers

The 2015 Paris agreement’s goal of limiting global warming to 1.5 degrees Celsius was thought to be the threshold for averting severe climate change impacts. But new research says even that level is too high to prevent the catastrophic consequences of sea level rise due to melting glaciers. John Yang speaks with Chris Stokes, one of the study’s authors, to learn more. PBS News is supported by - https://www.pbs.org/newshour/about/funders

PBS News Hour - Science - What the U.S. has accomplished in 250 years of innovation and what’s next

President Donald Trump went to Iowa on Thursday to start the countdown to the nation’s 250th Independence Day next year. To mark the anniversary, the nonpartisan Center for the Study of the Presidency and Congress is looking at 250 years of U.S. innovation. John Yang speaks with Glenn Nye, the center’s president and CEO, about the project. PBS News is supported by - https://www.pbs.org/newshour/about/funders

CrowdScience - Can we harness solar energy from other stars?

Listener Dickson Mukisa from Uganda has been gazing up at the stars. But he’s not making wishes. He wants to know whether we can harness their energy, in the same way we do with our OWN star – the sun. After all, they may seem small and twinkly to us, but each one is a gigantic flaming ball of energy, with a power outputs averaging around 40 quadrillion kilowatt-hours per year – EACH! With somewhere between 100 and 400 BILLION stars in our own galaxy alone, that’s a lot of power! Can we get ‘solar power’ from stars that are such a long way away from earth? And what might we use it for?

Alex Lathbridge heads to the University College London Observatory, to peer through the eyepiece of an enormous telescope and see some stars for himself. Professor Steve Fossey explains just how much of the light energy of the stars reaches us on earth. In other words, how BRIGHT they are.

Once the starlight reaches earth of course, we have to capture it. Could traditional solar panels do the job? Alex meets Professor Henry Snaith from the University of Oxford, to find out about the future of photovoltaic technology, and why it could all be heading out to space.

Once in space, things start getting weird! What if we made an enormous fleet of solar panels, and put them all into orbit around a star, soaking up every last drop of that precious energy? That might sound like science fiction, but the idea has been around for decades. It’s called a Dyson Sphere, or Dyson Swarm. Swedish researcher at the Insitute for Future Studies, Anders Sandberg explains how we might be able to build one around a neighbouring star... in around 10,000 years or so.

But maybe it’s not all about light. Finally, Alex explores the mysterious, invisible energy of the ‘solar wind’, with Pekka Janhunen, Finnish physicist and inventor of the “E-Sail”, which might be able to harness the power of the stellar wind, too.

Presenter: Alex Lathbridge Producer: Emily Knight Series Producer: Ben Motley

(Image: Astronomer looking at the starry skies with a telescope. Credit: m-gucci via Getty Images)